Chlorine-containing compounds are key players in stratospheric ozone depletion and they also play a role in the troposphere. Reservoir species 'store' reactive free radicals in less reactive forms for periods of time that are determined by their reactions. The reservoir species OClO reacts with HO free radicals, but the experimental reaction rate constants and product branching ratios are somewhat incomplete and uncertain. In the present work, the reaction mechanism, rate constants, and product branching ratios for HO + OClO were computed over wide temperature and pressure ranges, and compared with the experimental data. Stationary points on the singlet PES were calculated at high level of theory and the kinetics parameters were determined using several methods, including VTST and RRKM theory. The computed PES is in reasonable agreement with previous results and the computed rate constants agree with the NASA recommended rate constants within about a factor of two. The calculated pressure dependence is relatively minor over the atmospheric range. The calculated branching ratio for HOCl+O2 (the dominant product), which is less susceptible to computational errors, is in agreement with the very limited experimental data (~500 K) and increases as temperature is reduced to atmospheric conditions.

Theoretical study on the kinetics of the reaction HO+OClO

248th National Meeting (2014)

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